1 UBC International Training Fund Presents

Tensioning

The following material is intended to make you aware of the currently acceptable and recognized methods of performing the tasks described in this presentation. However, every possible application of these methods cannot be foreseen and the following material is not designed to cover every potential application. Therefore, you must always follow all current procedures and safety regulations whenever you perform any of the tasks discussed in this presentation.

4 WE SAID BEFORE - THERE ARE TWO COMMON WAYS TO PRE-LOAD A BOLT OR STUD: 1.TORQUE 2.TENSIONING  NOW THAT WE KNOW SOMETHING ABOUT TORQUE LET’S DISCUSS TENSIONING

5 TENSIONING TENSIONING = STRETCH THE BOLT, LET IT SPRING BACK

6 TENSIONING 1. HEAT 3 WAYS TO TENSION 2. HYDRAULIC TENSIONERS 3. MECHANICAL TENSIONERS 

7 TENSIONING TENSIONING WITH HEAT

Gas Bolt Heater

9 Objectives Correctly setup a gas bolt heater Properly adjust oxy-acetylene flame Correctly adjust air flow Safely operate a gas bolt heater

10 Design Heating causes a bolt to grow in length Relieves tension on bolt Gas Bolt Heater is machined from solid Stainless Steel A single bolt heater can be adapted to fit most bolt sizes by changing the heating tube diameter and length

11 Operation Select a heating tube that is 1/8” smaller than the hole in the bolt and approximately 3” shorter than the depth of the hole Install heating tube in bolt heater Use stainless steel reducing bushing for smaller heating tubes Use high temperature thread compound Tighten hand tight Connect air line to bolt heater Air pressure should be between PSI

12 Set oxygen pressure to 14 PSI Set Acetylene pressure to 7 PSI Use Victor #5-W gas welding tip Always use check valves Adjust flame to obtain a carburizing flame –Carburizing flame has an acetylene feather

13 Insert bolt heater into bolt Purge bolt cavity with air Turn air valve off Insert welding tip into gas bolt heater Gradually open air valve approximately 1/8 turn Observe color of heating tube through vent holes in gas bolt heater Maintain a cherry red color by adjusting air valve –More air is cooler –Less air is hotter

14 For proper operation a balance of pressure must be maintained between welding tip and heating chamber back pressure Excess back pressure will result in welding tip back-fire If back-fire occurs, close acetylene valve, remove welding tip from bolt heater, purge bolt cavity with air, and restart heating process

15 TENSIONING TENSIONING WITH HEAT (INDUCTION)

16 TENSIONING TENSIONING WITH HEAT CON’S: HOT SLOW INACCURATE HARD ON STUDS MUST HAVE HOLE ROUGH ON GASKETS PRO’S: MINIMUM MUSCLE

17 TENSIONING 1. HEAT 3 WAYS TO TENSION 2. HYDRAULIC TENSIONERS 3. MECHANICAL TENSIONERS 

18 TENSIONING HYDRAULIC TENSIONERS

19 TENSIONING HYDRAULIC TENSIONERS

20 VARIOUS TYPE OF HYDRAULIC TENSIONERS TOP CONNECT CYLINDER SIDE CONNECT CYLINDER HYDRAULIC NUT

21 TENSIONING 1. HEAT 3 WAYS TO TENSION 2. HYDRAULIC TENSIONERS 3. MECHANICAL TENSIONERS 

22 JACK SCREW TYPE

23 TORQUING THE JACK SCREWS MULTIPLIES WORKTAKES FOREVER TINY LOAD POINTS CAN’T CHECK RESULTS

The End